Silicon composition for coating substrates in supple material, in particular textile

Abstract

The invention concerns a coating composition capable of being cold vulcanised (EVF), characterised in that it comprises, in a mixture: (1) at least one polyorganosiloxane having, per molecule, at least two C 2 -C 6 alkenyl groups bound to silicon; (2) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms bound to silicon; (3) a catalytically effective amount of at least one catalyst, consisting of at least one metal belonging to the platinum group; (4) an adherence promoter; (5) optionally a reinforcing system which can be at least a polyorganosiloxane resin and/or a reinforcing filler; (6) optionally at least one cross-linkage inhibitor; (7) and mineral or organic hollow microspheres.

What is claimed is:  
     
       1. Coating composition which is cold-curing, comprising, as a mixture: 
       (1) at least one polyorganosiloxane having, per molecule, at least two C 2 -C 6 alkenyl groups linked to the silicon,  
       (2) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms linked to the silicon,  
       (3) a catalytically effective amount of at least one catalyst, composed of at least one metal belonging to the platinum group,  
       (4) an adhesion promoter comprising  
       at least one of the following compounds (4.1) and (4.2):  
       (4.1) at least one optionally alkoxylated organosilane containing, per molecule, at least one C 2 -C 6 alkenyl group,  
       (4.2) at least one organosilicon compound which includes at least one epoxy radical;  
       with optionally in addition:  
       (4.3) at least one metal M chelate and/or one metal alkoxide of the formula: (M(OJ) n , where n=the valency of M and J=a linear or branched C 1 -C 8 alkyl,  
       M being selected from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al or Mg,  
       (5) optionally, a reinforcing system, which may be at least one polyorganosiloxane resin, and/or at least one reinforcing filler,  
       (6) optionally, at least one crosslinking inhibitor, and  
       (7) expandable organic hollow microspheres having a polymer wall containing a liquid or a gas.  
     
     
       2. Composition according to  claim 1 , wherein the microspheres have a wall comprising polymers or copolymers prepared from vinyl chloride, vinylidene chloride, acrylonitrile, methyl methacrylate or strene monomers, or of blends of polymers and/or copolymers. 
     
     
       3. Composition according to  claim 1 , characterized in that the microspheres have an inorganic coating. 
     
     
       4. Composition according to  claim 1 , wherein the microspheres have a diameter after expansion of between 10 and 150 μm. 
     
     
       5. Composition according to  claim 1 , wherein, before expansion, the microspheres have a diameter of between 3 and 50 μm. 
     
     
       6. Composition according to  claim 1 , wherein the microspheres are present in an amount from 1 to 30% by weight, with respect to the total composition. 
     
     
       7. Composition according to  claim 1 , wherein the optionally alkoxylated organosiloxane (4.1) satisfies the following general formula:                    
       in which: 
       R 1 , R 2 , R 3  are hydrogen-containing or hydrocarbon radicals, which are the same or different from each other and represent hydrogen, a linear or branched C 1 -C 4  alkyl or a phenyl optionally substituted with at least one C 1 -C 3  alkyl,  
       U is a linear or branched C 1 -C 4 alkylene, or a divalent group of formula —COO-alkylene-, in which the alkylene residue is as defined above and is linked to the Si via W,  
       W is a valency bond,  
       R 4  and R 5  are radicals, which are the same or different and represent a linear or branched C 1 -C 4  alkyl,  
       x′=0 or 1, and  
       x=0 to 2.  
     
     
       8. Composition according to  claim 1 , wherein the organosilicon compound (4.2) is selected: 
       either from the substances (4.2a) satisfying the following general formula:                    
        in which:  
       R 6  is a linear or branched C 1 -C 4  alkyl radical,  
       R 7  is a linear or branched alkyl radical,  
       y is equal to 0, 1, 2or 3,                    
        with  
       E and D, which are the same or different radicals, selected from linear or branched C 1 -C 4 alkyls,  
       z, which is equal to 0 or 1,  
       R 8 , R 9 , R 10 , which are the same or different radicals, representing hydrogen or a linear or branched C 1 -C 4  alkyl,  
       or from the substances (4.2b) consisting of epoxy-functional polydiorganosiloxanes comprising:  
       (i) at least one siloxyl functional unit of formula:                X   p          G   q          SiO       4   -     (     p   +   q     )       2               (IV.2         b   1          )                             
        in which:  
       X is the radical as defined above in the case of formula (IV.2a)  
       G is a monovalent hydrocarbon group, free of any action unfavourable to the activity of the catalyst and selected from the alkyl groups having from 1 to 8 carbon atoms inclusive, optionally substituted by at least one halogen atom, and as well as from the aryl groups,  
       p=1 or 2,  
       q=0, 1 or 2,  
       p+q=1, 2 or 3,  
       and (2i) optionally at least one siloxyl functional unit of formula:                G   r          SiO       4   -   r     2               (IV.2         b   2          )                             
       in which G has the same meaning as above and r has a value of between 0 and 3. 
     
     
       9. Composition according to  claim 1 , wherein the metal chelate (4.3) comprises one or more ligands derived from a β-diketone. 
     
     
       10. Composition according to  claim 1 , wherein the alkoxy radical of the metal alkoxide (4.3) is an n-butoxy or an n-propoxy. 
     
     
       11. Composition according to  claim 1 , wherein the metal M of the chelate and/or of the alkoxide (4.3) is selected from the following list: Ti, Zr, Ge, Al, Mn. 
     
     
       12. Composition according to  claim 1 , wherein the promoter (4) comprises the compounds (4.1), (4.2) and (4.3) and in that the weight proportions between (4.1), (4.2) and (4.3), expressed in percentages by weight with respect to the total of the three, are as follows: 
       (4.1) is between 15 and 70,  
       (4.2) is between 70 and 15,  
       (4.3) is between 5 and 25;  
       and in that the weight ratio (4.2):(4.1) is between 2:1 and 0.5:1. 
     
     
       13. Composition according to  claim 1 , wherein the adhesion promoter is present in an amount of from 0.1 to 10% by weight with respect to all of the constituents, excluding the microspheres. 
     
     
       14. Composition according to  claim 1 , wherein the reinforcing system comprises polyorganosiloxane resin (5) which contains, in its structure, from 0.1 to 20% by weight of an alkenyl group or groups, said structure having at least two different functional units selected from the functional units of the M, D, T and Q types, at least one of these functional units being a functional unit of the T or Q type. 
     
     
       15. Composition according to  claim 1 , wherein the resin (5) is present in an amount of from 10 to 70% by weight with respect to all of the constituents. 
     
     
       16. Composition according to  claim 1 , wherein the reinforcing system comprises a silica reinforcing filler comprising. 
     
     
       17. Composition according to any one of  claim 1  to  16 , characterized in that it comprises a semireinforcing or bulking filler. 
     
     
       18. Composition according to  claim 1 , wherein the polyorganosiloxane (1) has: 
       (i) siloxyl functional units of formula:                T   a          Z   b          SiO       4   -     (     a   +   b     )       2               (   1.1   )                         
        in which:  
       T is an alkenyl groups,  
       Z is a monovalent hydrocarbon group, free of any action unfavourable to the activity of the catalyst and selected from alkyl groups having from 1 to 8 carbon atoms inclusive, optionally substituted by at least one halogen atom, and as well as from aryl groups,  
       a is 1 or 2, b is 0, 1 or 2 and a+b is between 1 and 3,  
       and (2i) optionally other siloxyl functional units of formula:                Z   c          SiO       4   -   c     2               (   1.2   )                         
       in which Z has the same meaning as above and c has a value of between 0 and 3. 
     
     
       19. Composition according to  claim 1 , characterized in that the polyorganosiloxane (2) contains 
       (i) siloxyl functional units of formula:                H   d          L   e          SiO       4   -     (     d   +   e     )       2               (   2.1   )                         
        in which:  
       L is a monovalent hydrocarbon group, free of any action unfavourable to the activity of the catalyst and selected from alkyl groups having from 1 to 8 carbon atoms inclusive, optionally substituted by at least one halogen atom, and as well as from aryl groups,  
       d is 1 or 2, e is 0, 1 or 2, d+e has a value of between 1 and 3,  
       and (2i) optionally other siloxyl functional units of average formula:                L   g          SIO       4   -   g     2               (   2.2   )                         
       in which L has the same meaning as above and g has a value of between 0 and 3. 
     
     
       20. Composition according to  claim 1 , wherein the proportions of (1), (2) and (5) are such that the ratio of the number of hydrogen atoms linked to the silicon in the polyorganosiloxane (2) to the number of alkenyl radicals provided by the polyorganosiloxane (1) and the resin (5) is between 0.4 and 10. 
     
     
       21. Composition according to  claim 1 , wherein the polyorganosiloxane (1) has a viscosity of greater than 1000 mPa·s at 25° C. 
     
     
       22. Two-component system, a precursor of the composition according to  claim 1 , wherein: 
       it is in the form of two separate parts A and B, these being intended to be mixed together to form the composition, and in that one of these parts A and B contains the catalyst (3) and only on the species, (1) or (2), of polyorganosiloxane and the other part contains the polyorganosiloxane (1) or (2) not present with the catalyst (3).  
     
     
       23. Flexible substrate, comprising a woven, knitted or non-woven fibrous textile, coated on one or both sides with a composition according to  claim 1 . 
     
     
       24. Coated substrate according to  claim 23 , wherein the fibrous substrate is a fabric having an open construction and a porosity>15 l/dm 2 /min according to the DIN 53 887 standard. 
     
     
       25. Airbag for protecting an occupant of a vehicle, formed from a coated fabric according to  claim 23 . 
     
     
       26. Composition according to  claim 1 , wherein the expandable microspheres are present in an amount of 3 to 30% by wt. of the total composition. 
     
     
       27. A coating composition according to  claim 1 , wherein the adhesion promoter comprises the compounds (4.1) and (4.2) or the compounds (4.1) and (4.3) or the compounds (4.2) and (4.3).